What&#39;s the difference between the getOrders in fulfillment api and trading api?

What's the difference between the getOrders in fulfillment api and trading api? And In https://developer.ebay.com/api-docs/sell/fulfillment/types/sel:LineItemReference claims lineItemId is based upon the concatenation of item ID/listing ID and the transaction ID, with a hyphen in between these two identifiers. But I just retrieved data in just a string of numbers, like: lineItemId 10013835657807 legacyItemId 132770083048 legacyVariationId 432078572042 There is no such a hyphen in lineitemid, so I can not get transactionid in this kind of returns.